title: Crystallization and preliminary X-ray analysis of the Thermoplasma acidophilum 20S proteasome in complex with protein substrates.
abstract: The 20S proteasome is a 700 kDa barrel-shaped proteolytic complex that is traversed by an internal channel which widens into three cavities: two antechambers and one central chamber. Entrance to the complex is restricted by the narrow opening of the channel, which only allows unfolded substrates to reach the active sites located within the central cavity. The X-ray structures of 20S proteasomes from different organisms with and without inhibitors bound have led to a detailed knowledge of their structure and proteolytic function. Nevertheless, the mechanisms that underlie substrate translocation into the 20S proteasome and the role of the antechambers remain elusive. To investigate putative changes within the proteasome that occur during substrate translocation, ;host-guest' complexes between the Thermoplasma acidophilum 20S proteasomes and either cytochrome c (cyt c) or green fluorescent protein (GFP) were produced and crystallized. Orthorhombic crystals belonging to space group P2(1)2(1)2(1), with unit-cell parameters a = 116, b = 207, c = 310 A (cyt c) and a = 116, b = 206, c = 310 A (GFP), were formed and X-ray diffraction data were collected to 3.4 A (cyt c) and 3.8 A (GFP) resolution.
authors.affiliation: Department of Molecular Structural Biology, Max-Planck Institute of Biochemistry, Am Klopferspitz 18, D-82152 Martinsried, Germany.
authors.forename: Karin
authors.initials: K
authors.lastname: Felderer
authors.forename: Matthew
authors.initials: M
authors.lastname: Groves
authors.forename: Joachim
authors.initials: J
authors.lastname: Diez
authors.forename: Ehmke
authors.initials: E
authors.lastname: Pohl
authors.forename: Susanne
authors.initials: S
authors.lastname: Witt
mesh_terms: D019843:Archaeal Proteins / Q000737:chemistry* / Q000302:isolation & purification; D003460:Crystallization; D018360:Crystallography, X-Ray; D046988:Proteasome Endopeptidase Complex / Q000737:chemistry* / Q000302:isolation & purification; D011485:Protein Binding; D013822:Thermoplasma / Q000378:metabolism*
chemical_list: D019843:Archaeal Proteins; D046988:Proteasome Endopeptidase Complex